The current system of testing cars to measure fuel economy and CO2 emissions is not fit for purpose. The gap between test results and real-world performance has become a chasm, increasing from 8% in 2001 to 31% in 2013 for private motorists. Mercedes cars have the biggest gap between test and real world performance, and less than 20% of the improvement in emissions measured in tests of Opel/Vauxhall cars is realised on the road.

This paper finds that distorted test results cost a typical motorist around €500 every year in additional fuel compared to official test results. By 2030, the widening gap will require drivers to cumulatively spend €1 trillion more on fuel and the EU to import 6 billion extra barrels of oil, worsening energy security and the EU’s balance of payments. The distorted test results cheat EU regulations, which are designed to reduce CO2 emissions, adding 1.5bn tonnes of CO2 to the atmosphere by 2030 and increasing the prospects of dangerous and uncontrolled climate change. They also reduce government car tax receipts, distorting sales in favour of the carmakers best able to manipulate tests rather than those making the most efficient cars.